For the first time in its existence, NASA is set to send two women astronauts on an all-women space walk scheduled to happen before Friday.

In October 1984, Kathryn Sullivan became the first American woman to complete a spacewalk, and there has been 220 spacewalks since December 1998. But so far, only 15 women have been on a spacewalk, albeit always with men, according to The Guardian.

This time, NASA is sending the two women astronauts -- Christina Koch and Jessica Meir -- who are already aboard the International Space Station (ISS), since March and September. They have been tasked with replacing a faulty power system on the outside of the ISS, which failed to activate after installing lithium-ion batteries, earlier this month. 

NASA states that the failure in the power system will not put the safety of the crew, operation and ongoing experiments in jeopardy. But the faulty power unit was preventing a set of batteries from providing increased station power, the space agency adds.

This isn't the first time that NASA has planned an all-female spacewalk: Koch and another NASA astronaut Anne McClain were selected for a spacewalk in March, earlier this year, a move which wasn't deliberately planned. As per npr, "Only after the two female astronauts were scheduled together, did they realize it would be the first all-female spacewalk."

Christina Koch (left) and Jessica Meir (right) (NASA)

However, the plan had to be shelved for a later date as the agency didn't have the right-sized spacesuits for both the women astronauts. The space agency had only one medium-sized suit at that time and so McClain was replaced by male astronaut Nick Hague.

This move was met with some disappointment. But over the next six months, NASA sent in a second medium spacesuit up to the ISS, according to the Guardian.

If everything goes according to plan, Koch and Meir will be the first women to be on an all-female spacewalk. While Koch has been on three spacewalks already, this will be Meir's first. The spacewalk will last about 5.5 hours, the npr reports.

You can catch the spacewalk live on NASA Television and the agency’s website.

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